International Research Journal of Engineering and Technology (IRJET)
Volume: 08 Issue: 09 | Sep 2021
www.irjet.net
e-ISSN: 2395-0056 p-ISSN: 2395-0072
Numerical Analysis on DI Diesel Engine by Varying Combustion Chamber Geometry Akhil Vijayan1, Dr. Benny Paul2 1M-tech
student, Dept. of Mechanical Engineering, M A College of Engineering, Kerala, India Dept. of Mechanical Engineering, M A College of Engineering, Kerala, India -----------------------------------------------------------------------***-----------------------------------------------------------------------2Professor,
Abstract- The usage of diesel engines compared to gasoline engines was increased recently due to its better performance and reduced emissions. Diesel engines have better brake thermal efficiency and lower carbon monoxide and hydrocarbon emissions but they have a problem of higher particulate and NOx emission. In diesel engines, the combustion chamber geometry plays a major role that it affects the mixing of air and fuel before the combustion starts. The present work is to improve the engine performance and emissions characteristics using different combustion chamber geometries (hemispherical, shallow depth and toroidal). In toroidal combustion chamber geometry, better mixing of air fuel takes place and generates high pressure and hence gives higher brake thermal efficiency. NOx emission is found to be higher while carbon monoxide and soot emissions are lower. It is concluded that for the better performance and reduced emissions, toroidal combustion chamber geometry is found to be the optimum design. Geometry is created by using SolidWorks and STAR-CD is used for the simulation.
depends mainly on the combustion chamber geometry. Proper air fuel mixture leads to proper combustion which increases the performance of the engine and power output and emissions from the engine can be reduced to a great extent. Extensive researches have been reported and going on regarding the optimization of combustion chamber designs, fuel preparation and treatment of exhaust gases. For the better performance of a diesel engine, the fuel that was injected has to evaporate quickly and form a mixture which can ignite easily at different regions of the combustion chamber. For complete combustion, the injected fuel has to mix properly with the air and form an ignitable mixture as early as possible. In diesel engines, the time available for the injected fuel to mix with air was very less, so the droplet size determines the efficiency of combustion. Hence the size of the injected fuel has to be as small as possible for better mixing. This can be achieved either by employing a high pressure injector or by the modification of combustion chamber geometry. Turbulence is essential for efficient mixing, evaporation and dissipation of injected fuel droplets. The geometry of the piston bowl can be designed to produce a squish and swirling action which can improve the fuel/air mixture before the ignition takes place. Some earlier numerical studies states that NOx can be reduced by changing the bowl depth.
Key Words: Combustion chamber geometry, Diesel engine, STAR-CD, Emissions.
1. INTRODUCTION The use of diesel engines for commercial purpose and gasoline engines for personal purpose was the earlier trend. But it was changed in recent years that diesel engines are used for the personal purpose also. This was mainly due to the better performance and emission characteristics of diesel engine like higher brake thermal efficiency, lower emissions, better power output, less fuel utilization, durability and reliability. Comparatively diesel engines have higher brake thermal efficiency and lower carbon monoxide and hydrocarbon emission. One of the main problems associated with diesel engines is that NOx emission and particulate matter are found to be higher. It affects mainly the design of diesel engines.
Combustion of the fuel inside the combustion chamber depend upon many factors like, fuel injection pressure, fuel injection timing, fuel properties, fuel spray pattern, fuel quantity, engine design such as shape of combustion chamber and position of injector, number and size of injection nozzle hole, air swirl and so on. The shape of combustion chamber geometry affects the atomization of fuel and resulting ignition process and is affected by the turbulence made by the cylinder bowl geometry. Air-fuel mixing impacts combustion and emission level in the engine. The present study describes the introduction of different piston bowl geometries like hemispherical, shallow depth and toroidal combustion chamber geometry into the engine. By using bowl geometries the momentum created will not get destroyed and proper mixing of air and fuel
Engine producers are extremely quick to design and build the combustion chamber carefully, since the factors like combustion, performance, emission and production of energy depends on the chamber geometry. Air fuel mixing
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